Synthesis of olefins from oxygen-free direct conversion of methane and catalysts thereof

ABSTRACT

The present invention is related to the preparation of a metal lattice-doping catalyst in an amorphous molten state, and the process of catalyzing methane to make olefins, aromatics, and hydrogen using the catalyst under oxygen-free, continuous flowing conditions. Such a process has little coke deposition and realizes atom-economic conversion. Under the conditions encountered in a fixed bed reactor (i.e. reaction temperature: 750˜1200° C.; reaction pressure: atmospheric pressure; the weight hourly space velocity of feed gas: 1000˜30000 ml/g/h; and fixed bed), conversion of methane is 8-50%. The selectivity of olefins is 30˜90%. And selectivity of aromatics is 10˜70%. There is no coking. The reaction process has many advantages, including a long catalyst life (&gt;100 hrs), high stability of redox and hydrothermal properties under high temperature, high selectivity towards target products, zero coke deposition, easy separation of products, good reproducibility, safe and reliable operation, etc., all of which are very desirable for industrial application.

FIELD OF THE INVENTION

The present invention is related to a method of olefins synthesis byoxygen-free direct conversion of methane under continuous flowconditions and the catalyst used, which presents no coke deposition andatom-economy conversion.

BACKGROUND OF THE INVENTION

Natural gas is an excellent clean energy resource, of which the primarycomponent is methane (CH₄). The world appears to have abundant reservesof methane, especially with the recent discoveries of significantdeposits of shale gas in continental North America and methane hydratein the sediments of the ocean floors, which is estimated to be at leasttwice of the amount of carbon in all other known fossil fuel reserves.

Over the past few decades, both the production and the consumption ofworld natural gas have increased continuously. The proportion of naturalgas in world primary energy production rose from 9.8% in 1950 to 24% atpresent, and was estimated to reach up to 29% in 2020. By that time,natural gas will become an important energy resource in the 21^(st)century. However, the consumption of natural gas is still not mature, inthe portion of natural gas used in chemical industry is low. Due to thedifficulty of methane activation and the high cost of raw chemicals(olefin, aromatics etc.) caused by the fluctuating market of crude oil,the research of efficient methane conversion to valuable products is notonly a scientific challenge but also an urgent need to alleviate theenergy crisis and to ensure a sustainable development.

There are two basic routes to produce valuable chemicals from methane,indirect and direct conversion. Currently, the most widely used methodis indirect conversion, i.e. methane is first converted to syngas withvarious C/H ratios by either reforming or partial oxidation, and thenraw chemicals and refined oil products are converted from syngas throughFischer-Tropsch synthesis, syngas to olefin, syngas to gasoline, ammoniasynthesis or many other processes. However, the indirect conversion ofmethane is always accompanied by complicated facilities, high productioncost, and especially large CO₂ emission. Therefore, the study of directmethane conversion to valuable chemicals has received particularattention recently.

Direct conversion of methane can be classified into three routescurrently: oxidative coupling of methane to ethylene (OCM), selectivepartial oxidation of methane to methanol and formaldehyde (SOM), andmethane dehydroaromatization to aromatics (MDA). Keller and Bhasin fromUCC reported the first case of the direct conversion of methane in 1982that methane oxidative coupled to ethylene at 1023 K led to 14% ofmethane conversion and 5% of ethylene selectivity. Although this processhas been optimized with methane conversion up to 20˜40%, ethyleneselectivity up to 50˜80%, and ethylene yield of 14˜25%, the scale-upapplication still suffer from many disadvantages such as hightemperature oxidative condition, over oxidation of methane to CO₂,separation of products, etc. The SOM process encounters similardifficulties: methanol and formaldehyde tend to further oxidation andleads to low selectivity.

In 1993, researchers from Dalian Institute of Chemical Physics (DICP)reported methane dehydroaromatization (MDA) for the formation ofaromatics (mainly C₆H₆) and H₂ at 973 K under non-oxidizing conditionsin a flow reactor, using a zeolite catalyst (HZSM-5) modified withmolybdenum, with the result of 6% of methane conversion and over 90%aromatics selectivity (exclusive of carbon deposit). Since this landmarkdiscovery, many researchers have worked on this process, and a plentifulamount of encouraging progresses have been made in catalyst preparation,reaction mechanism, deactivation mechanism, and so on. Nevertheless,industrial applications are restricted by the rapid carbon deposition ofthe catalyst.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is related to a method of olefins synthesis byoxygen-free direct conversion of methane under continuous flowconditions and its catalysts. The so-called oxygen-free conversion isthat methane can be converted directly in absence of molecular oxygen(O₂), elemental sulfur (S), or sulfur oxide compounds (such as SO₂,etc.).

The said catalysts are that metal elements are doped in the lattice ofamorphous-molten-state materials made from Si bonded with one or two ofC, N and O element. The said doping is lattice doping. The so-calledlattice doping is that the dopant metal elements exchange with thelattice elements in the doped materials, and the dopant metal elementsmay form or not form a specific chemical bonding (such as ionic bond,etc.) with other elements except the exchanged elements, which will leadto the metal dopant elements being confined in the lattice of the dopedmaterials, resulting in a specific catalytic performance.

Taking the total weight of the catalyst as 100%, the amount of thedopant metal is more than 0.001 wt. % but less than 10 wt. %

The so-called amorphous-molten-state materials are that the metal andsilicon-based materials are all in a molten state or surface in a moltenstate in the catalyst preparation, and then formed amorphous materialswith long-range disorder and short-range order after being cooled.

Preferably, the dopant metal elements of the said catalysts are one ormore of alkali metals, alkaline earth metals and transition metals.

Preferably, the said metal elements are one or more of Li, Na, K, Mg,Al, Ca, Sr, Ba, Y, La, Ti, Zr, Ce, Cr, Mo, W, Re, Fe, Co, Ni, Cu, Zn,Ge, In, Sn, Pb, Bi, Mn; and preferably one or more of Li, K, Mg, Al, Ca,Sr, Ba, Ti, Ce, Mn, Zn, Co, Ni, Fe.

Preferably, the types of the metal compounds are one or more of metaloxides, metal carbides, metal nitrides, metal silicides, and metalsilicates.

The said catalysts are silicon-based materials that comprise one or moreof O, C, and N, which is obtained by doping in its lattice metaldopants, forming a molten state, and solidifying the molten material.

Preferably, the precursors of dopant metal elements include one or moreof elemental metals, nitrates, halides, sulfates, carbonates,hydroxides, metal carbonyls, organometallic alkoxide with 1 to 5 Catoms, and organic acid salts with 1 to 5 C atoms.

The silicon source for preparing silicon-based materials for dopingincludes liquid silicon source or solid silicon source.

The said liquid silicon source preferably include, but not limited to,one or more of tetraethyl silicates, silicon tetrachlorides and anorganic silane compounds. The chemical formula of the organic silanecompounds are as follows:

wherein

n=0, 1, 2;

(m is 1 or ≧3),

(m is 0, 1 or 2) or

arylene, etc; R denotes one of hydroxyl group or methyl group;

P═—Cl, —NH₂, —HNCH₂CH₂NH₂, —NHR (R denotes alkyl, alkenyl or aryl with 1to 5 carbon atoms),

—N₃, —NCO, —SH, —CH═CH₂, —OCOCMe═CH₂,

X denotes the carbon-containing functional groups which can behydrolyzed or condensed, such as Cl, —OMe, —OCH₂CH₃, —OCH₂CH₂OCH₃, or—OAc.

The said solid silicon source preferably include, but not limited to,one or more of silica, silicon carbide, silicon nitride, elementalsilicon, wherein, the particle size of the solid silicon source ispreferably 10 nm-200 μm and the specific surface area is preferably0-500 m²/g.

The preparation method of the said catalysts is one of the followingsolid phase doping technologies, or a combination of two or more suchtechnologies.

The purpose of the following catalyst preparation is to improve thedispersion of the metal element in the silicon-based materials, and todope the metal element effectively in the lattice ofamorphous-molten-state materials made from Si bonded with one or more ofC, N, and O element.

The said solid phase doping technologies include the following:

The preparation methods of metal lattice-doped silicon-based catalystsinclude the following solid phase doping technologies, such as ChemicalVapor Deposition (CVD), Vapor phase Axial Deposition (VAD), Laserinduced Chemical Vapor Deposition (LCVD), doped sol-gel method, porousSi compound impregnation method.

Chemical Vapor Deposition (CVD): under the specific temperature(1100-2000° C.) and vacuum (10⁻⁴ Pa-10⁴ Pa), the silicon-based catalystswith metal dopants are obtained by the following procedures: 1) themixture of silicon vapor or SiCl₄ together with metallic vapor orvolatile metal salt (i.e. one or more of metal carbonyls, metalalkoxides of C atom number from 1 to 5, and organic acid salts of C atomnumber from 1 to 5) carried in carrier gas (i.e. one or more of N₂, He,H₂, Ar and Ke) reacts with water vapor; 2) then the products from theprocedure 1) are melted in air, inert gas, or vacuum; 3) finally theproducts from the procedure 2) are solidified to obtain the targetcatalysts.

Vapor Phase Axial Deposition (VAD): under the specific temperature(1100-2000° C.) and vacuum (10⁻⁴ Pa-10⁴ Pa), the silicon-based catalystswith metal dopants are obtained by the following procedure: 1) themixture of silicon vapor or SiCl₄ together with metallic vapor orvolatile metal salt (i.e. one or more of metal carbonyls, metalalkoxides of C atom number from 1 to 5, and organic acid salts of C atomnumber from 1 to 5) carried in H₂ reacts with water vapor; 2) then theproducts from the procedure 1) are deposited on the surface of a hightemperature device (i.e. one or more of corundum, silicon carbide,silicon nitride). The temperature of the device is controlled at acertain point between 500 and 1300° C.; 3) furthermore, the SOCl₂ gas ispassed through for dehydrating and drying; 4) then the products from theprocedure 3) are melted in air, inert gas, or vacuum; 5) the productsfrom the procedure 4) are solidified to obtain the target catalysts.

Laser Induced Chemical Vapor Deposition (LCVD): using laser as the heatsource, a technology-enhanced CVD is achieved by laser activation. Underthe specific temperature (1100-2000° C.) and vacuum (10⁻⁴ Pa-10⁴ Pa),the silicon-based catalysts with metal dopants are obtained by followingprocedure: 1) the mixture of silicon vapor or SiCl₄ together withmetallic vapor or volatile metal salt (i.e. one or more of metalcarbonyls, metal alkoxides of C atom number from 1 to 5, and organicacid salts of C atom number from 1 to 5) carried in carrier gas (i.e.one or more of N₂, He, H₂, Ar, and Ke) reacts with water vapor; 2) thenthe products from the procedure 1) are melted in air, inert gas, orvacuum; 3) finally the products from the procedure 2) are solidified toobtain the target catalysts.

Doped sol-gel method: The liquid silicon source and organic or inorganicmetal salt (such as one or more of nitrates, halides, sulfates,carbonates, hydroxides, organic acid salts of C atom number from 1 to10, and metal alkoxides of C atom number from 1 to 10) are used asprecursors, which are dissolved in a mixture of water and ethanol (theweight content of water in the mixture is 10-100%). After the hydrolysisand condensation of the precursors, a stable transparent sol system isformed from the above-mentioned solution. After aging the sol, athree-dimensional network structure of the gel is formed slowly by thepolymerization between sol particles. After drying, melting in air, ininert gas or under vacuum and then being solidified, the targetcatalysts are obtained.

Porous Si-based materials impregnation method: Using a porous solidsilicon-based material (such as one or more of silica, silicon carbide,and silicon nitride) as a catalyst support, the support is impregnatedin the solution of metal salt for metal loading. After the impregnation,the slurry is dried. The resulting powder is melted in air, in inert gasor under vacuum and then solidified, the target catalysts are obtained.

The preparation methods of the said catalysts include an importantmelting process, which includes a melting step such as high-temperatureair melting process, high-temperature inert gas melting process, orhigh-temperature vacuum melting process. The preferable temperature ofthe melting process is 1300-2200° C.

Preferably, the inert gas in the high-temperature inert gas meltingprocess includes one or more of N₂, He, Ar, and Ke.

The melting time is preferably 2-10 hrs.

The vacuum in high-temperature vacuum melting process is preferably0.01-100 Pa.

The aim of the melting process is to dope the metal element in thesilicon-based materials, and to effectively remove the introduced —OHgroups of the preparation process.

Preferably, the said solidification is that the catalyst preparationinvolves an important cooling process after the melting process; and thesaid cooling process includes rapid cooling or natural cooling.

The said rapid cooling process includes one or more process of gascooling, water cooling, oil cooling and liquid nitrogen cooling. Therate of the rapid cooling process is preferably 50-800° C./s.

Preferably, the type of oil in the said oil cooling process includes oneor more of mineral oil (saturated hydrocarbon content of 50-95%, Scontent of ≦0.03%, a viscosity index (VI) of 80 to 170), rapeseed oil,silicone oil, PAO (poly-α olefin). The type of gas in the said gascooling process includes one or more of inert gas (He, Ne, Ar, Ke), N₂and air.

After being melted and solidified, the amorphous molten state catalystsinvolve an important step of grinding or molding process.

The particle size after being ground is preferably 10 nm-10 cm.

The said molding process is that the amorphous-molten-state catalystsbeing melted are manufactured to obtain the specific shape (such as,honeycomb-shaped monolithic catalyst, etc.) for meeting various reactionprocesses, or directly manufactured into tubular reactor (withoutaddition of a catalyst).

The said catalysts that has metal dopants in one or moreamorphous-molten-state materials made from Si bonded with one or more ofC, N and O element can be expressed A@SiO₂, A@SiC, A@Si₃N₄,A@SiC_(x)O_(y) (4x+2y=4), A@SiO_(y)N_(z) (2y+3z=4), A@SiC_(x)N_(z)(4x+3z=4), A@SiC_(x)O_(y)N_(z) (4x+2y+3z=4; x, y and z are notsimultaneously equal to zero), and the range of x, y and z are 0-1, 0-2,and 0-4/3, respectively. “A” denotes the metal dopants.

In A@SiO₂, by partially replacing Si atoms, the metal element A isinserted in the lattice of silica (Si), and bonds with the adjacent Oatoms (A-O). In A@SiC catalysts, by partially replacing Si atoms, themetal element A is inserted in the lattice of silicon carbide (SiC), andbonds with the adjacent C or Si atoms (A-C or Si-A). In A@Si₃N₄, bypartially replacing Si atoms, the metal element A is inserted thelattice of silicon nitride (Si₃N₄), and bonds with the adjacent N atoms(A-N). In A@SiC_(x)O_(y), by partially replacing Si or C atoms, themetal element A is inserted the lattice of SiC_(x)O_(y), and bonds withthe adjacent C, O or Si atoms (A-C, A-O or A-Si). In A@SiO_(y)N_(z), bypartially replacing Si or N atoms, the metal element A is inserted thelattice of SiO_(y)N_(z), and bonds with the adjacent N, O or Si atoms(A-N, A-O or A-Si). In A@SiC_(x)N_(z), by partially replacing Si or Catoms, the metal element A is inserted in the lattice of SiC_(x)N_(z),and bonds with the adjacent C, N or Si atoms (A-C, A-N or A-Si). InA@SiC_(x)O_(y)N_(z), by partially replacing Si, N or C atoms, the metalelement A is inserted in the lattice of SiC_(x)O_(y)N_(z), and bondswith the adjacent C, N, O or Si atoms (A-C, A-O, A-N or A-Si).

The present invention involves a method of olefins synthesis byoxygen-free direct conversion of methane, which includes three reactionmodes, i.e., fluidized bed mode, moving bed mode, and fixed bed mode.

The present invention involves a method of olefins synthesis byoxygen-free direct conversion of methane, of which the feed gas includesone or more of inert and non-inert gas besides methane. With a volumecontent of 0˜95%, the inert gas includes one or two of nitrogen (N₂),helium (He), neon (Ne), argon (Ar), and krypton (Ke). The non-inert gasincludes one or two of carbon monoxide (CO), hydrogen (H₂), carbondioxide (CO₂), water (H₂O), monohydric alcohol (the number of carbonatom is from 1 to 5), dihydric alcohol (the number of carbon atom isfrom 2 to 5), alkanes (the number of carbon atom is from 2 to 8); thevolume ratio of non-inert gas to methane is 0˜15% and the volume contentof methane in the feed gas is 5˜100%.

The present invention involves a method of olefins synthesis byoxygen-free direct conversion of methane, of which a pretreatment to thecatalysts before the reaction is necessary. The atmosphere of thepretreatment process is feed gas or hydrocarbons and their derivatives,which contains one or a mixture from alkanes of carbon atom number from2 to 10, alkenes of carbon atom number from 2 to 10, alkyne of carbonatom number from 2 to 10, monohydric alcohol of carbon atom number from1 to 10, dihydric alcohol of carbon atom number from 2 to 10, aldehydeof carbon atom number from 1 to 10, carboxylic acid of carbon atomnumber from 1 to 10, aromatics of carbon atom number from 6 to 10.Pretreatment temperature is 800˜1000° C.; pretreatment pressure is under0.1˜1 Mpa, preferably atmospheric pressure. The weight hourly spacevelocity of feed gas is 500˜3000 ml/g/h, preferably 800˜2400 ml/g/h.

The present invention involves a method of olefins synthesis byoxygen-free direct conversion of methane, of which the reaction processincludes continuous flow reaction mode or batch reaction mode. Under thecontinuous flow reaction mode, the reaction temperature is 750˜1200° C.,preferably 800˜1150° C.; the reaction pressure is under 0.1˜1 MPa,preferably atmospheric pressure; the weight hourly space velocity offeed gas is 1000˜30000 ml/g/h, and preferably 4000˜20000 ml/g/h. Underthe batch reaction mode, the reaction pressure is preferably 1-20 MPa;the reaction time is preferably ≧5 min.

The present invention involves a method of olefins synthesis byoxygen-free direct conversion of methane, which the olefin productsinclude one or two of ethylene, propylene, or butylene, and the jointproducts in the reaction include aromatics and hydrogen. The aromaticproducts include one or more of benzene, toluene, xylene, o-xylene,m-xylene, ethylbenzene, and naphthalene.

Based on the research of the methane dehydroaromatization process, thisinvention discloses a metal doped silicon-based catalyst for olefins,aromatics and hydrogen production by direct conversion of methane underoxygen-free and continuous flow reaction mode. Compared with theprevious oxygen-free methane conversion process, this method has thefollowing characteristics:

1. Reaction Process

1) High olefin selectivity (30-90%);

2) The selectivity of the aromatic co-products is achieved to 10-70%;

3) Other than a little coke deposition in the initial, the follow-upreaction process presents zero coke deposition;

4) The products can be easily separated.

2. Catalysts

1) Simple preparation method and low cost;

2) High mechanical strength and good thermal conductivity;

3) microporous or mesoporous materials not necessary;

4) Fabricating arbitrarily different shapes and specifications accordingto reaction conditions and reaction processes;

5) High stability under the atmosphere of redox and hydrothermalcondition at 800˜1150° C.;

6) Long catalyst life (>100 hrs) due to zero coke deposition and uniquestructure of the catalyst.

In summary, the said reaction process has many advantages, such as longlife of catalysts, high stability, high selectivity of target products,zero coke deposition, easy separation of products, good reproducibility,safe and reliable operation and among others, which are very importantfor industrial application.

Although it seems that there are some similarities in the productsdistribution between the present invention and the methanedehydroaromatization, there are fundamental differences, such as incatalysts and reaction mechanism. Firstly, a microporous zeolite supportis necessary for methane dehydroaromatization process. Secondly, thecurrent accepted reaction mechanism for methane dehydroaromatization isshown in Scheme 1. Methane is dissociated on the surface of theresulting active sites (such as MoC_(x), WC, Re) to produce CH_(x)species; subsequently, CH_(x) species are coupled on the surface ofzeolite supported catalyst to form the C₂H_(y) species; then C₂H_(y)species is coupled and cyclized on the BrΠnsted acidic sites of thezeolite, in which aromatics is formed by the shape selectivity ofzeolite channel. (J. Energy Chem. 2013, 22, 1-20)

However, the catalysts of the present patent are that metal elementsdoped in the lattice of materials with amorphous molten state made fromSi bonded with one or more of C, N and O element. The reaction mechanismis that methane is induced by the active species (dopant metal in thelattice) to produce .CH₃ radicals, which are further coupled anddehydrogened to obtain the olefins, aromatics and hydrogen (Scheme 2).

The differences between the present invention and the methanedehydroaromatization are as follows: 1) it is necessary for the methanedehydroaromatization to possess channels of zeolite with specific sizeand structure, as well as acidic sites of zeolite with certain amountand type. Whereas the catalysts in the present patent are amorphousmolten state materials without channel and acid; 2) the mechanism ofmethane dehydroaromatization is a synergistic interaction between activeMo species and acidic sites of zeolite, while the present patent is aradical induction mechanism.

In the present patent, the methane conversion is 8-50%; olefinselectivity is 30-90%; aromatic selectivity is 10-70%. The said reactionprocess using the claimed catalysts has many advantages, such as longlife of catalysts (>100 hrs), high stability of redox and hydrothermalconditions in high temperature, high selectivity of target products,zero coke deposition, easy separation of products, good reproducibility,safe and reliable operation and among others, which are very desirablefor industrial application.

DESCRIPTION OF FIGURES

FIG. 1 XRD pattern of 0.5 wt. % Ca-0.5 wt. % Fe @SiO₂ catalyst

FIG. 2 XPS spectra of Fe doping 6H—SiC(0001)

FIG. 3 HRTEM image of the metal lattice-doping catalyst

EMBODIMENTS 1. Catalyst Preparation

The preparation methods of silicon-based catalysts with metal dopantsinclude the following solid phase doping technologies, such as ChemicalVapor Deposition (CVD), Vapour phase Axial Deposition (VAD), Laserinduced Chemical Vapor Deposition (LCVD), metal doping sol-gel method,porous Si-based materials impregnation method, powder doping method andso on. The catalysts are marked as: A@SiO_(x)C_(y)N_(z).

The preparation of A@SiO₂ catalysts (example 1, 2, 3, 4, 5, 7); thepreparation of A@SiOC_(0.5) catalysts (example 6); the preparation ofA@Si₃C₄ catalysts (example 8, 9, 10); the preparation of A@Si₃N₄catalysts (example 11); the preparation of A@SiOC_(0.35)N_(0.2)catalysts (example 12); the preparation of A/SiO₂ catalysts (example 13)(Active species is highly dispersed on the support.)

Example 1 Chemical Vapor Deposition (CVD)

The vapor phase in the high-temperature reaction furnace is formed bybubbling 30 mL/min of carrier gas (10 vol. % of H₂ and 90 vol. % of He)into an 30 mL of ethanol solution dissolving 17 g of SiCl₄ and 94 mg ofCo₂(CO)₈. The mist vapor mixture sprayed from the center of combustor ishydrolyzed and melted to form a uniform SiO₂ material doped with Co at1200° C. The material is melted at 1400° C. in vacuum (10 Pa) for 6 h.The Co doped silica catalyst, 0.5 wt. % Co@SiO₂, is obtained aftersubsequent quenching in cold water.

Example 2

Chemical Vapor Deposition (CVD)

The vapor phase in the high-temperature reaction furnace is formed bybubbling 30 mL/min of carrier gas (10 vol. % of H₂ and 90 vol. % of He)into an 30 mL of ethanol solution dissolving 17 g of SiCl₄, 94 mg ofCo₂(CO)₈ and 86.9 mg Ni(CO)₄. The mist vapor mixture sprayed from thecenter of combustor is hydrolyzed and melted at 1200° C. to form auniform SiO₂ material doped with Co and Ni. The material is furthermelted at 1400° C. in vacuum (10 Pa) for 6 h. The Co/Ni doping silicacatalyst, 0.5 wt. % Co-0.5 wt. % Ni@SiO₂, is obtained after subsequentquenching in cold water.

Example 3 Vapor Phase Axial Deposition (VAD)

The vapor phase in the high-temperature reaction furnace is formed bybubbling 30 mL/min of carrier gas (10 vol. % of H₂ and 90 vol. % of He)into an 30 mL of ethanol solution dissolving 17 g of SiCl₄, 94 mg ofCo₂(CO)₈. The mist vapor mixture sprayed from the center of combustor ishydrolyzed and axial deposited on the surface of alumina support at1200° C. to form a uniform SiO₂ material doped with Co. The material ismelted at 1400° C. in vacuum (10 Pa) for 6 h. The Co doping silicacatalyst, 0.5 wt. % Co@SiO₂, is obtained after subsequent quenching incold water.

Example 4 Vapor Phase Axial Deposition (VAD)

The vapor phase in the high-temperature reaction furnace is formed bybubbling 30 mL/min of carrier gas (10 vol. % of H₂ and 90 vol. % of He)into an 30 mL of ethanol solution dissolving 17 g of SiCl₄, 94 mg ofCo₂(CO)₈ and 86.9 mg Ni(CO)₄. The mist vapor mixture sprayed from thecenter of combustor is hydrolyzed and axial deposited on the surface ofalumina support at 1200° C. to form a uniform SiO₂ material doped withCo and Ni. The obtained material is melted at 1400° C. in vacuum (10 Pa)for 6 h. The Co doping silica catalyst, 0.5 wt. % Co-0.5 wt. % Ni@SiO₂,is obtained after subsequent quenching in cold water.

Example 5 Metal Doping Sol-Gel Method

A metal doping silica gel is formed by stirring 20 mL oftetraethoxysilane (TEOS), 120 mg of Co(NO₃)₂.6H₂O, 117.1 mgCa(NO₃)₂.4H₂O and 30 mL ethanol in 24 g 15% nitric acid solution at 60°C. for 24 h. The gel is dried in rotary evaporator at 80° C. for 2 h andmelted at 1400° C. in He atmosphere for 6 h. The Co/Ca doped silicacatalyst, 0.5 wt. % Ca-0.5 wt. % Co@SiO₂, is obtained after subsequentquenching in cold water.

Example 6

The vapor phase in the high-temperature reaction furnace is formed bybubbling 30 mL/min of carrier gas (10% v of H₂ and 90% v of He) into an30 mL of ethanol solution dissolving 17 g of SiCl₄ and 94 mg ofCo₂(CO)₈. The mist vapor mixture sprayed from the center of combustor ishydrolyzed and melted at 1200° C. to form a uniform SiO₂ material dopedwith Co. The material is treated in a mixed gas (10% v of CH₄ and 90% vof He) at 2000° C. and afterwards melted at 1400° C. in vacuum (10 Pa)for 6 h. The Co doped catalyst, 0.5 wt. % Co@SiOC_(0.5), is obtainedafter subsequent quenching in cold water.

Example 7 Porous Si-Based Materials Impregnation Method

The catalyst is prepared by impregnating 6 g of porous silica powder ina solution of 117 mg of Ca(NO₃)₂.4H₂O and 137.3 mg of Co(NO₃)₂.6H₂O in10 mL of water. The slurry is dried by stirring and aging for 24 h at120° C. and afterwards melted at 1400° C. in vacuum (10 Pa) for 6 h. TheCo/Ca doped catalyst, 0.5 wt. % Ca-0.5 wt. % Co@SiO₂, is obtained aftersubsequent melting process at 1400° C. in vacuum (10 Pa) for 6 h.

Example 8 Porous Si-Based Materials Impregnation Method

The metal doped is prepared by impregnating 6 g of porous siliconcarbide powder in a solution of 216 mg of Fe(NO₃)₃.9H₂O in 10 mL ofwater. The slurry is dried by stirring and aging for 24 h at 120° C. Thedry powder is melted at 2000° C. in vacuum (10 Pa) for 6 h to form auniform SiC material doped with Fe. The Fe doping catalyst, 0.5 wt. %Fe@SiC, is obtained after subsequent quenching in rapeseed oil.

Example 9

A metal doped silica gel is formed by stirring 20 mL oftetraethoxysilane (TEOS), 120 mg of Co(NO₃)₂.6H₂O, 117.1 mgCa(NO₃)₂.4H₂O and 30 mL ethanol in 24 g 15% nitric acid solution at 60°C. for 24 h. The gel is dried in rotary evaporator at 80° C. for 2 h andmelted with carbon at 2000° C. for 2.5 h to form a uniform SiC materialdoped with Co and Ca. The Co/Ca doping silica catalyst, 0.5 wt. % Ca-0.5wt. % Co@SiOC_(0.5), is obtained after subsequent quenching in coldwater.

Example 10

A metal doped silica gel is formed by stirring 20 mL oftetraethoxysilane (TEOS), 120 mg of Co(NO₃)₂.6H₂O, 117.1 mgCa(NO₃)₂.4H₂O and 30 mL ethanol in 24 g 15% nitric acid solution at 60°C. for 24 h. The gel is dried in rotary evaporator at 80° C. for 2 h andcalcined with carbon at 2000° C. for 12 h to form a uniform SiC materialdoped with Co and Ca. The Co/Ca doping silica catalyst, 0.5 wt. % Ca-0.5wt. % Co@SiC, is obtained after subsequent quenching in cold water.

Example 11

The catalyst (0.5 wt. % Ca-0.5 wt. % Co@SiO₂) mentioned in example 5 istreated in nitriding furnace at 1150-1200° C. at NH₃ atmosphere for 4 hand then 1350-1450° C. at NH₃ atmosphere for 18-36 h, until all becomefar nitride to form a uniform Si₃N₄ material doped with Co and Ca. Theresulting powder is 0.5 wt. % Ca-0.5 wt. % Co@Si₃N₄.

Example 12

The catalyst (0.5 wt. % Co@SiOC_(0.5)) mentioned in example 6 is treatedin nitriding furnace at 1150-1200° C. at NH₃ atmosphere for 4 h and then1350-1450° C. at NH₃ atmosphere for 7.5 h to form a uniformSiOC_(0.35)N_(0.3) material doped with Co. The resulting powder is 0.5wt. % Ca-0.5 wt. % Co@SiOC_(0.35)N_(0.3).

Example 13

The metal loading catalyst is prepared by impregnating 6 g of silicasupport in a solution of 94 mg of Co₂(CO)₈ in 10 mL of water. The slurryis stirred vigorously for 12 h and aging for 24 h at 60° C. The Coloading catalyst, 0.5 wt. % Co/SiO₂, is obtained after subsequentcalcination at 550° C. in air for 6 h.

For the further understanding of the invention, the following examplesare given for purpose of illustration only and should not be regarded aslimiting in any way.

2. Catalyst Characterization

a) XRD Characterization of 0.5 Wt. % Ca-0.5 Wt. % Fe @SiO₂ Catalyst

The XRD pattern of the catalyst indicates that there is only a broaddiffraction peak at 23°, which shows an amorphous characteristic peak ofSiO₂ (FIG. 1). Meanwhile, the diffraction peaks of Fe and Ca cannot beobserved. All of these results are significantly different from thezeolite catalyst system.

b) Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES)Leaching Characterization

The so-called ICP-AES acid leaching method is that the metal atomsoutside the Si-based support can be dissolved in dilute nitric acid (Thedilute nitric acid can only dissolves the metal, but it cannot dissolvethe supports), while those protected by the Si-based support lattice orSi-based support cannot be dissolved, and meanwhile the ICP-ASE resultscan obtain a degree of acid leaching (i.e., a ratio of surface loadingsto surface loading and doping loading). Firstly, the 0.5 wt. % Co@SiO₂catalyst was leached by dilute nitric acid, and the results showed thatno Co atoms can be detected by ICP-AES, and further revealed the Coatoms have inserted the lattice of Si-based support. Subsequently, the0.5 wt. % Co@SiO₂ catalyst was leached by HF acid (the HF acid candissolve either metal atoms or Si-based support), the results showedthat all of Co atoms can be detected by ICP-AES, and the leaching amountis equal to the loading amount of the Co@SiO₂ catalyst. The aboveresults show that all of Co atoms have been inserted inside the latticeof Si-based support, and almost no Co atoms can be detected on thesurface of Si-based support.

c) XPS Characterization of Fe-Doped 6H—SiC(0001)

As can be seen from the result of XPS Si2p (FIG. 2), there is an obviousshoulder peak at the binding energy of 99.6 eV, which attributes to theFeSi_(x) species. Furthermore, the results show Fe atom could substitutethe lattice C atoms, and then the Fe atoms could bond with Si atom toform the FeSi_(x) species.

d) ICP-AES Leaching Characterization of 0.5 Wt. % Co/SiO₂ Catalyst

Firstly, the 0.5 wt. % Co@SiO₂ catalyst was leached by dilute nitricacid, and the results showed that all of Co atoms can be detected byICP-AES, and the leaching amount is equal to the catalyst loadingamount. Furthermore, the results show that all of Co atoms havedispersed on the surface of Si-based support, and almost no Co atoms canbe inserted inside the lattice of Si-based support.

e) High Resolution Transmission Microscopy (HR-TEM) Image of the MetalLattice-Doping Catalyst

Furthermore, HR-TEM was used to characterize the dispersion andconfiguration of the metal lattice-doping catalyst prepared by the metaldoping sol-gel method (Example 5 of catalyst preparation), FIG. 3. Ascan be seen from this image, we can observe a clear crystal structure(white circles), FIGS. 3A and 3B. The HR-TEM results prove that theso-called amorphous molten state catalysts exhibited the structure withlong-range disorder and short-range order.

3. Under the Oxygen-Free and Continuous Flow Conditions, Methane isDirectly Converted to Olefin, Aromatics and Hydrogen

All of the above catalyst prior to use need to be ground and sieved to20-30 mesh as a backup.

All of the following reaction examples are achieved in a continuous flowmicro-reaction apparatus, which is equipped with gas mass flow meters,gas deoxy and dehydration units, and online product analysischromatography. The tail gas of reaction apparatus is connected with themetering valve of chromatography, and thus periodic and real-timesampling and analysis will be achieved. The feed gas is composed of 10vol. % N₂ and 90 vol. % CH₄ without specification, in which the nitrogen(N₂) is used in an internal standard. To achieve the online productanalysis, the Agilent 7890A chromatography with dual detector of FID andTCD is used. The FID detector with HP-1 capillary column is used toanalyze the light olefin, light alkane and aromatics; and the TCDdetector with Hayesep D packed column is used to analyze the lightolefin, light alkane, methane, hydrogen and N₂ internal standard.According to the carbon balance before and after reaction, methaneconversion, product selectivity and coke deposition selectivity arecalculated by the method from the two Chinese patents (CN1247103A,CN1532546A).

Example 1

The 0.75 g 0.5 wt. % Co@SiO₂ catalyst prepared by the Example 1 ofcatalyst preparation method was loaded in the fix-bed reactor, and thenpurged by Ar gas (25 ml/min) for 20 mins Maintaining a constant flowrate of Ar, the reactor is programmed from room temperature up to 950°C. at a heating rate of 10° C./min. And then the weight hourly spacevelocity (WHSV) of feed gas was adjusted to 4840 ml/g/h. After the WHSVbeing kept 20 mins, the reaction results were analyzed by the onlinechromatography. The results were as follows: 8.2% of methane conversion,47.6% and 1.0 μmol/g_(catalyst)/s of ethylene selectivity and ethylenegeneration rate, 26.1% and 0.2 μmol/g_(catalyst)/s of benzeneselectivity and benzene generation rate, 26.2% and 0.1μmol/g_(catalyst)/s of Naphthalene selectivity and Naphthalenegeneration rate, and 5.4 μmol/g_(catalyst)/s of hydrogen generationrate.

Examples 2-7

The 0.75 g 0.5 wt. % Co@SiO₂ catalyst prepared by the Examples 2-7 ofcatalyst preparation method was loaded in the fix-bed reactor, and thenpurged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flowrate of Ar, the reactor is programmed from room temperature up to thefollowing temperatures (Table 1) at a heating rate of 10° C./min. Andthen the weight hourly space velocity (WHSV) of feed gas was adjustedaccording to following values (Table 1). The results of methaneconversion and products selectivity are as follows:

TABLE 1 Ben- Naphtha- Methane Ethylene zene lene Exam- Temp.¹ WHSV²Conv.³ Sel.⁴ Sel. Sel. ple (° C.) (ml/g/h) (%) (%) (%) (%) 2 750 16002.5 70 16 14 3 850 2200 5.6 65 20 15 4 900 3600 6.4 55 22 23 5 950 51007.9 52 23 25 6 980 8400 15.2 48 24 28 7 1050 15200 9.8 46 25 29 ¹Temp.denotes temperature; ²WHSV denotes the weight hourly space velocity;³Conv. denotes conversion; ⁴Sel. Denotes selectivity.

Example 8

The 1.5 g 0.5 wt. % Ca-0.5 wt. % Co@SiC catalyst prepared by Example 10of the catalyst preparation method was loaded in the fix-bed reactor,and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining aconstant flow rate of Ar, the reactor is programmed from roomtemperature up to 950° C. at a heating rate of 10° C./min. And then theweight hourly space velocity (WHSV) of feed gas was adjusted to 4840ml/g/h. After the WHSV being kept 20 mins, the reaction results wereanalyzed by the online chromatography. The results were as follows:8.02% of methane conversion, 46.4% and 1.2 μmol/g_(catalyst)/s ofethylene selectivity and ethylene generation rate, 26.2% and 0.2μmol/g_(catalyst)/s of benzene selectivity and benzene generation rate,27.3% and 0.1 μmol/g_(catalyst)/s of Naphthalene selectivity andNaphthalene generation rate, and 6.4 μmol/g_(catalyst)/s of hydrogengeneration rate.

Examples 9-13

The 1.5 g 0.5 wt. % Ni-0.5 wt. % Co@SiO₂ catalyst prepared by Example 4of the catalyst preparation method was loaded in the fix-bed reactor,and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining aconstant flow rate of Ar, the reactor is programmed from roomtemperature up to following temperatures (Table 1) at a heating rate of10° C./min. And then the weight hourly space velocity (WHSV) of feed gaswas adjusted to following value (Table 2). The results of methaneconversion and products selectivity were as follows:

TABLE 2 Ben- Naphtha- Methane Ethylene zene lene Temp.¹ WHSV² Conv.³Sel.⁴ Sel. Sel. Example (° C.) (ml/g/h) (%) (%) (%) (%) 9 750 1600 2.268 16 16 10 850 2200 5.9 62 23 15 11 900 3600 6.8 51 24 25 12 950 51007.5 50 25 25 13 980 8400 14.3 49 23 28 ¹Temp. denotes temperature; ²WHSVdenotes the weight hourly space velocity; ³Conv. denotes conversion;⁴Sel. Denotes selectivity.

Example 14

The 0.75 g 0.5 wt. % Ca-0.3 wt. % Al@SiO₂ catalyst prepared by Example 5of catalyst preparation method was loaded in the fix-bed reactor, andthen purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constantflow rate of Ar, the reactor is programmed from room temperature up to950° C. at a heating rate of 10° C./min. And then the weight hourlyspace velocity (WHSV) of feed gas was adjusted to 4840 ml/g/h. After theWHSV being kept 20 mins, the reaction results were analyzed by theonline chromatography. After 100 hours, the results were as follows:7.8% of methane conversion, 46.8% and 0.9 μmol/g_(catalyst)/s ofethylene selectivity and ethylene generation rate, 27.2% and 0.2μmol/g_(catalyst)/s of benzene selectivity and benzene generation rate,25.8% and 0.1 μmol/g_(catalyst)/s of Naphthalene selectivity andNaphthalene generation rate, and 5.2 μmol/g_(catalyst)/s of hydrogengeneration rate.

Example 15

The 0.75 g 0.5 wt. % Co@SiOC_(0.5) catalyst prepared by Example 6 ofcatalyst preparation method was loaded in the fix-bed reactor, and thenpurged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flowrate of Ar, the reactor was programmed from room temperature up to 950°C. at a heating rate of 10° C./min. And then the weight hourly spacevelocity (WHSV) of feed gas was adjusted to 4840 ml/g/h. After the WHSVbeing kept 20 mins, the reaction results were analyzed by the onlinechromatography. The results were as follows: 8.2% of methane conversion,47.3% and 1.2 μmol/g_(catalyst)/s of ethylene selectivity and ethylenegeneration rate, 22.0% and 0.23 μmol/g_(catalyst)/s of benzeneselectivity and benzene generation rate, 29.2% and 0.14μmol/g_(catalyst)/s of Naphthalene selectivity and Naphthalenegeneration rate, and 6.4 μmol/g_(catalyst)/s of hydrogen generationrate.

Examples 16-19

The 0.75 g 0.5 wt. % Co@SiOC_(0.5) catalyst prepared by Example 6 of thecatalyst preparation method was loaded in the fix-bed reactor, and thenpurged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flowrate of Ar, the reactor was programmed from room temperature up tofollowing temperature (Table 1) at a heating rate of 10° C./min. Andthen the weight hourly space velocity (WHSV) of feed gas was adjusted tofollowing value (Table 3). The results of methane conversion andproducts selectivity were as follows:

TABLE 3 Ben- Naphth- Methane Ethylene zene alene Temp.¹ WHSV² Conv.³Sel.⁴ Sel. Sel. Example (° C.) (ml/g/h) (%) (%) (%) (%) 16 750 1600 3.072 12 16 17 850 2200 5.3 64 21 15 18 900 3600 7.1 53 24 23 19 950 51007.9 47 25 28 20 980 8400 15.5 45 23 32 ¹Temp. denotes temperature; ²WHSVdenotes the weight hourly space velocity; ³Conv. denotes conversion;⁴Sel. Denotes selectivity.

Example 21

The 0.75 g 0.5 wt. % Ca-0.3 wt. % Zn@SiOC_(0.5) catalyst prepared byExample 6 of the catalyst preparation method was loaded in the fix-bedreactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaininga constant flow rate of Ar, the reactor was programmed from roomtemperature up to 1000° C. at a heating rate of 10° C./min. And then theweight hourly space velocity (WHSV) of feed gas was adjusted to 10000ml/g/h. After the WHSV being kept 20 mins, the reaction results wereanalyzed by the online chromatography. The results were as follows: 31%of methane conversion, 52.1% and 5.7 μmol/g_(catalyst)/s of ethyleneselectivity and ethylene generation rate, 21.3% and 0.8μmol/g_(catalyst)/s of benzene selectivity and benzene generation rate,26.4% and 0.6 μmol/g_(catalyst)/s of Naphthalene selectivity andNaphthalene generation rate, and 28 μmol/g_(catalyst)/s of hydrogengeneration rate.

Example 22

The 0.75 g 0.5 wt. % Ca-0.3 wt. % Co@SiOC_(0.5) catalyst prepared by theExample 9 of catalyst preparation method was loaded in the fix-bedreactor, and then purged with the Ar gas (25 ml/min) for 20 mins.Maintaining a constant flow rate of Ar, the reactor is programmed fromroom temperature up to 950° C. at a heating rate of 10° C./min. And thenthe weight hourly space velocity (WHSV) of feed gas (10 vol. % CH₄, 5vol. % N₂ and 85 vol. % He) was adjusted to 4840 ml/g/h. After the WHSVbeing kept 20 mins, the reaction results were analyzed by the onlinechromatography.

The results were as follows: 7.1% of methane conversion, 51.3% and 0.1μmol/g_(catalyst)/s of ethylene selectivity and ethylene generationrate, 14.3% and 0.01 μmol/g_(catalyst)/s of benzene selectivity andbenzene generation rate, 7.4% and 0.003 μmol/g_(catalyst)/s ofNaphthalene selectivity and Naphthalene generation rate, 26.6% of cokeselectivity, and 0.5 μmol/g_(catalyst)/s of hydrogen generation rate.

Example 23

The 0.75 g 0.5 wt. % Ca-0.6 wt. % Co@SiOC_(0.5) catalyst prepared by theExample 6 of catalyst preparation method was loaded in the fix-bedreactor, and then purged with the Ar gas (25 ml/min) for 20 mins.Maintaining a constant flow rate of Ar, the reactor is programmed fromroom temperature up to 950° C. at a heating rate of 10° C./min. And thenthe weight hourly space velocity (WHSV) of feed gas (88 vol. % CH₄, 2vol. % CO, 8 vol. % N₂ and 2 vol. % He) was adjusted to 4840 ml/g/h.After the WHSV being kept 20 mins, the reaction results were analyzed bythe online chromatography. The results were as follows: 8.5% of methaneconversion, 40.4% and 0.8 μmol/g_(catalyst)/s of ethylene selectivityand ethylene generation rate, 25.6% and 0.2 μmol/g_(catalyst)/s ofbenzene selectivity and benzene generation rate, 31.4% and 0.1μmol/g_(catalyst)/s of Naphthalene selectivity and Naphthalenegeneration rate, 0.4% of coke selectivity, and 5.5 μmol/g_(catalyst)/sof hydrogen generation rate.

Example 24

The 0.75 g 0.2 wt. % Mg-0.3 wt. % Zn@SiOC_(0.5) catalyst prepared by theExample 9 of catalyst preparation method was loaded in the fix-bedreactor, and then purged with the Ar gas (25 ml/min) for 20 mins.Maintaining a constant flow rate of Ar, the reactor is programmed fromroom temperature up to 950° C. at a heating rate of 10° C./min. And thenthe weight hourly space velocity (WHSV) of feed gas (5.4 vol. % CH₃OH,85 vol. % CH₄ and 9.6 vol. % N₂) was adjusted to 4840 ml/g/h. After theWHSV being kept 20 mins, the reaction results were analyzed by theonline chromatography. The results were as follows: 6% of methaneconversion, 64.5% and 0.9 μmol/g_(catalyst)/s of ethylene selectivityand ethylene generation rate, 15.1% and 0.07 μmol/g_(catalyst)/s ofbenzene selectivity and benzene generation rate, 8.9% and 0.2μmol/g_(catalyst)/s of Naphthalene selectivity and Naphthalenegeneration rate, 3.6% and 0.05 μmol/g_(catalyst)/s of ethaneselectivity, 7.8% of coke selectivity, and 9.3 μmol/g_(catalyst)/s ofhydrogen generation rate.

Example 25

The 0.75 g 0.5 wt. % Ca-0.3 wt. % Co@SiOC_(0.5) catalyst prepared by theExample 9 of the catalyst preparation method was loaded in the fix-bedreactor, and then purged with the Ar gas (25 ml/min) for 20 mins.Maintaining a constant flow rate of Ar, the reactor is programmed fromroom temperature up to 950° C. at a heating rate of 10° C./min. And thenthe weight hourly space velocity (WHSV) of the feed gas (5.4 vol. %CH₃OH, 85 vol. % CH₄ and 9.6 vol. % N₂) was adjusted to 10000 ml/g/h.After the WHSV being kept 20 mins, the reaction results were analyzed bythe online chromatography. The results were as follows: 22% of methaneconversion, 60.9% and 6.6 μmol/g_(catalyst)/s of ethylene selectivityand ethylene generation rate, 14.3% and 0.5 μmol/g_(catalyst)/s ofbenzene selectivity and benzene generation rate, 7.6% and 0.2μmol/g_(catalyst)/s of Naphthalene selectivity and Naphthalenegeneration rate, 2.3% and 0.3 μmol/g_(catalyst)/s of ethane selectivity,14.1% of coke selectivity, and 39 μmol/g_(catalyst)/s of hydrogengeneration rate.

Example 26

The 0.75 g 0.5 wt. % Mn-1.1 wt. % Fe@SiOC_(0.5) catalyst prepared byExample 6 of the catalyst preparation method was loaded in the fix-bedreactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaininga constant flow rate of Ar, the reactor is programmed from roomtemperature up to 950° C. at a heating rate of 10° C./min. And then theweight hourly space velocity (WHSV) of feed gas (5 vol. % CO₂, 85 vol. %CH₄ and 10 vol. % N₂) was adjusted to 4840 ml/g/h. After the WHSV beingkept 20 mins, the reaction results were analyzed by the onlinechromatography. The results were as follows: 8.3% of methane conversion,42.2% and 0.8 μmol/g_(catalyst)/s of ethylene selectivity and ethylenegeneration rate, 25.3% and 0.2 μmol/g_(catalyst)/s of benzeneselectivity and benzene generation rate, 23.6% and 0.1μmol/g_(catalyst)/s of Naphthalene selectivity and Naphthalenegeneration rate, 3.2% and 0.06 μmol/g_(catalyst)/s of ethaneselectivity, 7.1% of coke selectivity, and 2.0 μmol/g_(catalyst)/s ofhydrogen generation rate.

Example 27

The 0.5 g 0.2 wt. % K-0.6 wt. % Fe@SiO₂ catalyst prepared by Example 5of the catalyst preparation method (replacing Co(NO₃)₂.6H₂O andCa(NO₃)₂.4H₂O with KNO₃ and Fe(NO₃)₃.9H₂O) was loaded in the fix-bedreactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaininga constant flow rate of Ar, the reactor was programmed from roomtemperature up to 950° C. at a heating rate of 10° C./min. And then theweight hourly space velocity (WHSV) of feed gas was adjusted to 10800ml/g/h. After the WHSV being kept 20 mins, the reaction results wereanalyzed by the online chromatography. The results were as follows: 9.8%of methane conversion, 43% of ethylene selectivity, 25% of benzeneselectivity, 27% of Naphthalene selectivity, 2% of ethane selectivity,and 3% of coke selectivity.

Example 28

The 0.65 g 0.1 wt. % K-0.6 wt. % Pb@SiOC_(0.5) catalyst prepared byExample 6 of the catalyst preparation method (replacing Co(NO₃)₂.6H₂Oand Ca(NO₃)₂.4H₂O with KNO₃ and Pb(NO₃)₂) was loaded in the fix-bedreactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaininga constant flow rate of Ar, the reactor is programmed from roomtemperature up to 950° C. at a heating rate of 10° C./min. And then theweight hourly space velocity (WHSV) of feed gas was adjusted to 10800ml/g/h. After the WHSV being kept 20 mins, the reaction results wereanalyzed by the online chromatography. The results were as follows: 7.4%of methane conversion, 47% of ethylene selectivity, 23% of benzeneselectivity, 28% of Naphthalene selectivity, and 2% of ethaneselectivity.

Example 29

The 0.65 g 0.1 wt. % K-0.6 wt. % Ti@SiO₂ catalyst prepared by Example 5of the catalyst preparation method (replacing Co(NO₃)₂.6H₂O andCa(NO₃)₂.4H₂O with KNO₃ and tetrabutyl titanate) was loaded in thefix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins.Maintaining a constant flow rate of Ar, the reactor was programmed fromroom temperature up to 950° C. at a heating rate of 10° C./min. Then theweight hourly space velocity (WHSV) of feed gas was adjusted to 10800ml/g/h. After the WHSV being kept 20 mins, the reaction results wereanalyzed by the online chromatography. The results were as follows: 7.4%of methane conversion, 47% of ethylene selectivity, 23% of benzeneselectivity, 28% of Naphthalene selectivity, and 2% of ethaneselectivity.

Example 30

The 0.65 g 0.1 wt. % Mg-0.6 wt. % Ce@SiO₂ catalyst prepared by Example 5of the catalyst preparation method (replacing Co(NO₃)₂.6H₂O andCa(NO₃)₂.4H₂O with Mg(NO₃).2H₂O and Ce (NO₃)₃.6H₂O) was loaded in thefix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins.Maintaining a constant flow rate of Ar, the reactor was programmed fromroom temperature up to 950° C. at a heating rate of 10° C./min. Then theweight hourly space velocity (WHSV) of feed gas was adjusted to 10800ml/g/h. After the WHSV being kept 20 mins, the reaction results wereanalyzed by the online chromatography. The results were as follows:10.2% of methane conversion, 49% of ethylene selectivity, 23% of benzeneselectivity, 25% of Naphthalene selectivity, 3% of ethane selectivity,and 3% of coke selectivity.

Example 31

The 0.65 g 0.1 wt. % Mg-0.3 wt. % Sn@SiO₂ catalyst prepared by Example 5of the catalyst preparation method (replacing Co(NO₃)₂.6H₂O andCa(NO₃)₂.4H₂O with Mg(NO₃).2H₂O and SnCl₄.5H₂O) was loaded in thefix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins.Maintaining a constant flow rate of Ar, the reactor was programmed fromroom temperature up to 950° C. at a heating rate of 10° C./min. Then theweight hourly space velocity (WHSV) of feed gas was adjusted to 11200ml/g/h. After the WHSV being kept 20 mins, the reaction results wereanalyzed by the online chromatography. The results were as follows: 6.2%of methane conversion, 43% of ethylene selectivity, 24% of benzeneselectivity, 28% of Naphthalene selectivity, 2% of ethane selectivity,and 3% of coke selectivity.

Example 32

The 0.75 g 0.5 wt. % Fe@SiC catalyst prepared by Example 5 of thecatalyst preparation method was loaded in the fix-bed reactor, and thenpurged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flowrate of Ar, the reactor was programmed from room temperature up to 950°C. at a heating rate of 10° C./min. Then the weight hourly spacevelocity (WHSV) of feed gas was adjusted to 15200 ml/g/h. After the WHSVbeing kept 20 mins, the reaction results were analyzed by the onlinechromatography. The results were as follows: 12.5% of methaneconversion, 44% of ethylene selectivity, 22% of benzene selectivity, 24%of Naphthalene selectivity, 2% of ethane selectivity, 6% of cokeselectivity, and 7.0 μmol/g_(catalyst)/s of hydrogen generation rate.

Example 33

The 0.75 g 0.8 wt. % Ca-1.1 wt. % Fe@SiOC_(0.5) catalyst prepared byExample 9 of the catalyst preparation method was loaded in the fix-bedreactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaininga constant flow rate of Ar, the reactor was programmed from roomtemperature up to 950° C. at a heating rate of 10° C./min. And then theweight hourly space velocity (WHSV) of feed gas (5.0 vol. % H₂O, 85.5vol. % CH₄ and 9.5 vol. % N₂) was adjusted to 10000 ml/g/h. After theWHSV being kept 20 mins, the reaction results were analyzed by theonline chromatography. The results were as follows: 12.1% of methaneconversion, 34.7% and 1.2 μmol/g_(catalyst)/s of ethylene selectivityand ethylene generation rate, 25.6% and 0.3 μmol/g_(catalyst)/s ofbenzene selectivity and benzene generation rate, 25.1% and 0.2μmol/g_(catalyst)/s of Naphthalene selectivity and Naphthalenegeneration rate, 2.4% and 0.08 μmol/g_(catalyst)/s of ethaneselectivity, 5.3% of CO selectivity, and 12 μmol/g_(catalyst)/s ofhydrogen generation rate.

Example 34

The 0.75 g 0.5 wt. % Ca-0.5 wt. % Co@Si₃N₄ catalyst prepared by Example11 of the catalyst preparation method was loaded in the fix-bed reactor,and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining aconstant flow rate of Ar, the reactor is programmed from roomtemperature up to 950° C. at a heating rate of 10° C./min. Then theweight hourly space velocity (WHSV) of feed gas (90 vol. % CH₄ and 10vol. % N₂) was adjusted to 5000 ml/g/h. After the WHSV being kept 20mins, the reaction results were analyzed by the online chromatography.The results were as follows: 14% of methane conversion, 40.1% and 1.3μmol/g_(catalyst)/s of ethylene selectivity and ethylene generationrate, 22.3% and 0.3 μmol/g_(catalyst)/s of benzene selectivity andbenzene generation rate, 26.2% and 0.2 μmol/g_(catalyst)/s ofNaphthalene selectivity and Naphthalene generation rate, 11.4% of cokeselectivity, and 8 μmol/g_(catalyst)/s of hydrogen generation rate.

Example 35

The 0.75 g 0.5 wt. % Co@SiOC_(0.35)N_(0.2) catalyst prepared by Example12 of the catalyst preparation method was loaded in the fix-bed reactor,and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining aconstant flow rate of Ar, the reactor was programmed from roomtemperature up to 950° C. at a heating rate of 10° C./min. And then theweight hourly space velocity (WHSV) of feed gas (90 vol. % CH₄ and 10vol. % N₂) was adjusted to 4840 ml/g/h. After the WHSV being kept for 20mins, the reaction results were analyzed by the online chromatography.The results were as follows: 16.2% of methane conversion, 46% and 1.4μmol/g_(catalyst)/s of ethylene selectivity and ethylene generationrate, 27.5% and 0.35 μmol/g_(catalyst)/s of benzene selectivity andbenzene generation rate, 26.5% and 0.3 μmol/g_(catalyst)/s ofNaphthalene selectivity and Naphthalene generation rate, and 8μmol/g_(catalyst)/s of hydrogen generation rate.

Example 36

The 0.75 g 0.5 wt. % Co/SiO₂ catalyst prepared by Example 13 of thecatalyst preparation method was loaded in the fix-bed reactor, and thenpurged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flowrate of Ar, the reactor was programmed from room temperature up to 950°C. at a heating rate of 10° C./min. And then the weight hourly spacevelocity (WHSV) of the feed gas (90 vol. % CH₄ and 10 vol. % N₂) wasadjusted to 4840 ml/g/h. After the WHSV being kept for 20 mins, thereaction results were analyzed by the online chromatography. The resultswere as follows: 18.5% of methane conversion, <3% of ethyleneselectivity, <1% of benzene selectivity and Naphthalene selectivity,and >96% of coke selectivity.

In summary, under the conditions encountered in a fixed bed reactor(i.e. reaction temperature: 750˜1200° C.; reaction pressure: atmosphericpressure; the weight hourly space velocity of feed gas: 1000˜30000ml/g/h; and fixed bed), conversion of methane is 8-50%. The selectivityof olefins is 30˜90%. And selectivity of aromatics is 10˜70%. There isno coking. The reaction process has many advantages, including a longcatalyst life (>100 hrs), high stability of redox and hydrothermalproperties under high temperature, high selectivity towards targetproducts, zero coke deposition, easy separation of products, goodreproducibility, safe and reliable operation, etc., all of which arevery desirable for industrial application.

We claim:
 1. A method of oxygen-free coupling of methane to olefins,wherein: methane as feed gas can be directly converted to olefins andjoint production of aromatics and hydrogen; said catalysts are thatmetal elements doped in the lattice of the amorphous-molten-statematerials made from Si bonded with one or more of C, N and O; the dopingamount of the metal lattice-doped catalysts is more than 0.001 wt. %,but less than 10 wt. % of total weight of the catalyst.
 2. The methodaccording to claim 1, wherein the reaction temperature is 750-1200° C.,preferably 800-1150° C.
 3. The method according to claim 1, wherein acatalyst pretreatment process should be executed before the reaction:the atmosphere of the pretreatment process is feed gas, hydrocarbons ortheir derivatives, which contain at least one selected from alkanes with2 to 10 carbon atoms, alkenes with 2 to 10 carbon atoms, alkyne with 2to 10 carbon atoms, monohydric alcohol with 1 to 10 carbon atoms,dihydric alcohol with 2 to 10 carbon atoms, aldehyde with 1 to 10 carbonatoms, carboxylic acid with 1 to 10 carbon atoms, and aromatics with 6to 10 carbon atoms; pretreatment temperature is 800-1000° C.;pretreatment pressure is under 0.1˜1 Mpa, preferably atmosphericpressure; the weight hourly space velocity of feed gas is 500˜3000ml/g/h, preferably 800˜2400 ml/g/h.
 4. The method according to claim 1or 3, wherein: the feed gas is methane or mixture of methane and othergases in the oxygen-free coupling of methane to olefins; besidesmethane, the feed gas includes possibly one or two of inert gases ornon-inert gases; the inert gases include one or more of nitrogen (N₂),helium (He), neon (Ne), argon (Ar), and krypton (Ke), and the volumecontent of inert gas in the feed gas is 0˜95%; the non-inert gasesinclude one or more of carbon monoxide (CO), hydrogen (H₂), carbondioxide (CO₂), water vapor (H₂O), monohydric alcohol with 1 to 5 carbonatoms, dihydric alcohol with 2 to 5 carbon atoms, and alkanes with 2 to8 carbon atoms, and the volume ratio of non-inert gas to methane is0˜15%; the volume content of methane in the feed gas is 5˜100%.
 5. Themethod according to claim 1, 2, 3 or 4, wherein: the facility ofoxygen-free coupling of methane to olefins is fluidized bed, moving bed,or fixed bed; the pressure of reaction with continuous flow is under0.05˜1 MPa, preferably atmospheric pressure; the weight hourly spacevelocity of feed gas is 1000˜30000 ml/g/h, preferably 4000˜20000 ml/g/h.6. The method according to claim 1, wherein: the products of the saidolefin are one or more of ethylene, propylene and butylene, and thejoint products in the reaction include aromatics and hydrogen; thearomatic products include one or more of benzene, toluene, xylene,o-xylene, m-xylene, ethylbenzene, and naphthalene.
 7. The methodaccording to claim 1, wherein: the dopant metal elements of the saidcatalysts are one or more of alkali metals, alkaline earth metals andtransition metals; the dopant metal element chemically bonds with one ormore of the elements of Si, O, C and N in the catalysts; the dopingamount of metal element in the metal lattice-doped catalysts ispreferably 0.001%˜8 wt. %.
 8. The method according to claim 1, wherein:besides the dopant metal element in the said materials, one or more ofmetals or metal compounds can be loaded on the surface of saidmaterials; the loading amount of metals or metal compounds is 0.1˜8 wt.%; the types of the metal compounds are one or more of metal oxides,metal carbides, metal nitrides, metal silicides, and metal silicates. 9.The method according to claim 1, 7 or 8, wherein: the said metalelements are selected from one or more of Li, Na, K, Mg, Al, Ca, Sr, Ba,Y, La, Ti, Zr, Ce, Cr, Mo, W, Re, Fe, Co, Ni, Cu, Zn, Ge, In, Sn, Pb, Biand Mn; and preferably one or more of Li, K, Mg, Al, Ca, Sr, Ba, Ti, Ce,Mn, Zn, Co, Ni and Fe.
 10. The method according to claim 1, 7 or 8,wherein: the preparation methods of the said catalysts include one ormore of the following solid phase doping technologies: the said solidphase doping technologies are as follows: Chemical Vapor Deposition(CVD): under the specific temperature (1100-2000° C.) and vacuum (10⁻⁴Pa-10⁴ Pa), the silicon-based catalysts with dopant metal are obtainedby the following procedures: 1) the mixture of silicon vapor or SiCl₄together with metallic vapor or volatile metal salt (i.e. one or more ofmetal carbonyls, metal alkoxides of C atom number from 1 to 5, andorganic acid salts of C atom number from 1 to 5) inlet by carrier gas(i.e. one or more of N₂, He, H₂, Ar and Ke) reacts with water vapor; 2)then the products from the procedure 1) are melted in air, inert gas, orvacuum; 3) finally the products from the procedure 2) are solidified toobtain the target catalysts; Vapor Phase Axial Deposition (VAD): underthe specific temperature (1100-2000° C.) and vacuum (10⁻⁴ Pa-10⁴ Pa),the silicon-based catalysts with dopant metal are obtained by thefollowing procedure: 1) the mixture of silicon vapor or SiCl₄ togetherwith metallic vapor or volatile metal salt (i.e. one or more of metalcarbonyls, metal alkoxides of C atom number from 1 to 5, and organicacid salts of C atom number from 1 to 5) inlet by H₂ reacts with watervapor; 2) then the products from the procedure 1) are deposited on thesurface of the device with high melting point (i.e. one or more ofcorundum, silicon carbide, silicon nitride); the temperature of thedevice is controlled at a certain point between 500 and 1300° C.; 3)furthermore, the SOCl₂ gas is passed through for dehydrating and drying;4) then the products from the procedure 3) are melted in air, inert gas,or vacuum; 5) the products from the procedure 4) are solidified toobtain the target catalysts; Laser Induced Chemical Vapor Deposition(LCVD): using laser as the heat source, a technology-enhanced CVD isachieved by laser activation; under the specific temperature (1100-2000°C.) and vacuum (10⁻⁴ Pa-10⁴ Pa), the silicon-based catalysts with dopingmetal are obtained by following procedure: 1) the mixture of siliconvapor or SiCl₄ together with metallic vapor or volatile metal salt (i.e.one or more of metal carbonyls, metal alkoxides of C atom number from 1to 5, and organic acid salts of C atom number from 1 to 5) inlet by thereaction between carrier gas (i.e. one or more of N₂, He, H₂, Ar, andKe) reacts with water vapor; 2) then the products from the procedure 1)are melted in air, inert gas, or vacuum; 3) finally the products fromthe procedure 2) are solidified to obtain the target catalysts; Dopedsol-gel method: the liquid silicon source and organic or inorganic metalsalt (such as one or more of nitrates, halides, sulfates, carbonates,hydroxides, organic acid salts of C atom number from 1 to 10, and metalalkoxides of C atom number from 1 to 10) are used as precursors, whichare dissolved in a mixture of water and ethanol (the weight content ofwater in the mixture is 10-100%); after the hydrolysis and condensationof the precursors, stable transparent sol system is formed from theabove-mentioned solution; after aging the sol, a three-dimensionalnetwork structure of the gel is formed slowly by the polymerizationbetween sol particles after drying in air, inert gas or vacuum and beingsolidified, the target catalysts are obtained; Porous Si-based materialsimpregnation method: using a porous solid silicon-based material (suchas one or more of silica, silicon carbide, and silicon nitride) as acatalyst support, the support is impregnated in the solution of metalsalt for metal loading; after the impregnation, the slurry is dried; theresulting powder is melted in air, inert gas or vacuum and thensolidified, the target catalysts are obtained; the preparation methodsof the said catalysts include an important melting process, whichincludes such as high-temperature air melting process, high-temperatureinert gas melting process, or high-temperature vacuum melting process;the preferable temperature of the melting process is 1300-2200° C.; theinert gas in the high-temperature inert gas melting process includes oneor more of N₂, He, Ar and Ke; the vacuum in high-temperature vacuummelting process is preferably 0.01-100 Pa.
 11. The method according toclaim 10, wherein: the said solidification is that the catalystpreparation involves an important cooling process after the meltingprocess; and the said cooling process includes rapid cooling or naturalcooling; the said rapid cooling process includes one or more of gascooling, water cooling, oil cooling and liquid nitrogen cooling; therate of the rapid cooling process is preferably 50-800° C./s; the typeof oil in the said oil cooling process includes one or more of mineraloil (saturated hydrocarbon content of 50-95%, S content of ≦0.03%, aviscosity index (VI) of 80-170), rapeseed oil, silicone oil, and PAO(poly-α olefin); the type of gas in the said gas cooling processincludes one or more of inert gases (He, Ne, Ar, Ke), N₂ and air. 12.The method according to claim 10, wherein the melting time is preferably2-10 hrs.
 13. The method according to claim 10, wherein: after beingmelted and solidified, the amorphous-molten-state catalysts involve animportant step of grinding or molding process; the particle size afterbeing ground is preferably 10 nm 10 cm; the said molding process is thatthe amorphous-molten-state catalysts being melted are manufactured toobtain the specific shape to meet various reaction processes, ordirectly manufactured into tubular reactors.
 14. Catalysts for thesynthesis of olefins from oxygen-free direct conversion of methaneaccording to claim 1, wherein: the said catalysts are that metalelements doped in the lattice of amorphous-molten-state materials madefrom Si bonded with one or more of C, N, and O element; the dopingamount of the metal lattice-doped catalysts is more than 0.001 wt. %,but less than 10 wt. % of total weight of the catalyst.
 15. The catalystaccording to claim 14, wherein: the dopant metal elements of the saidcatalysts are one or more of alkali metals, alkaline earth metals andtransition metals, and the dopant metal element chemically bonds withone or more of the elements of Si, O, C and N in the materials; thedoping amount of the metal element in the metal lattice-doped catalystsis preferably 0.001-8 wt. %.
 16. The catalyst according to claim 14,wherein: besides the dopant metal element in the said materials, one ormore of metal or metal compounds can be loaded on the surface of thesaid materials; the loading of metal or metal compounds is 0.1-8 wt. %;the types of the metal compounds are one or more of metal oxides, metalcarbides, metal nitrides, metal silicides, and metal silicates.
 17. Thecatalyst according to claim 14, 15 or 16, wherein: the said metalelements are one or more of Li, Na, K, Mg, Al, Ca, Sr, Ba, Y, La, Ti,Zr, Ce, Cr, Mo, W, Re, Fe, Co, Ni, Cu, Zn, Ge, In, Sn, Pb, Bi, Mn; andpreferably one or more of Li, K, Mg, Al, Ca, Sr, Ba, Ti, Ce, Mn, Zn, Co,Ni and Fe.
 18. The catalyst according to claim 14, 15 or 16, wherein:the preparation methods of the said catalysts include one or more of thefollowing solid phase doping technologies: the said solid phase dopingtechnologies are as follows: Chemical Vapor Deposition (CVD): under thespecific temperature (1100-2000° C.) and vacuum (10⁻⁴ Pa-10⁴ Pa), thesilicon-based catalysts with dopant metal are obtained by the followingprocedures: 1) the mixture of silicon vapor or SiCl₄ together withmetallic vapor or volatile metal salt (i.e. one or more of metalcarbonyls, metal alkoxides of C atom number from 1 to 5, and organicacid salts of C atom number from 1 to 5) inlet by carrier gas (i.e. oneor more of N₂, He, H₂, Ar and Ke) reacts with water vapor; 2) then theproducts from the procedure 1) are melted in air, inert gas, or vacuum;3) finally the products from the procedure 2) are solidified to obtainthe target catalysts; Vapor Phase Axial Deposition (VAD): under thespecific temperature (1100-2000° C.) and vacuum (10⁻⁴ Pa-10⁴ Pa), thesilicon-based catalysts with dopant metal are obtained by the followingprocedure: 1) the mixture of silicon vapor or SiCl₄ together withmetallic vapor or volatile metal salt (i.e. one or more of metalcarbonyls, metal alkoxides of C atom number from 1 to 5, and organicacid salts of C atom number from 1 to 5) inlet by H₂ reacts with watervapor; 2) then the products from the procedure 1) are deposited on thesurface of the device with high melting point (i.e. one or more ofcorundum, silicon carbide, silicon nitride); the temperature of thedevice is controlled at a certain point between 500 and 1300° C.; 3)furthermore, the SOCl₂ gas is passed through for dehydrating and drying;4) then the products from the procedure 3) are melted in air, inert gas,or vacuum; 5) the products from the procedure 4) are solidified toobtain the target catalysts; Laser Induced Chemical Vapor Deposition(LCVD): using laser as the heat source, a technology-enhanced CVD isachieved by laser activation; under the specific temperature (1100-2000°C.) and vacuum (10⁻⁴ Pa-10⁴ Pa), the silicon-based catalysts with dopingmetal are obtained by following procedure: 1) the mixture of siliconvapor or SiCl₄ together with metallic vapor or volatile metal salt (i.e.one or more of metal carbonyls, metal alkoxides of C atom number from 1to 5, and organic acid salts of C atom number from 1 to 5) inlet by thereaction between carrier gas (i.e. one or more of N₂, He, H₂, Ar, andKe) reacts with water vapor; 2) then the products from the procedure 1)are melted in air, inert gas, or vacuum; 3) finally the products fromthe procedure 2) are solidified to obtain the target catalysts; Dopedsol-gel method: the liquid silicon source and organic or inorganic metalsalt (such as one or more of nitrates, halides, sulfates, carbonates,hydroxides, organic acid salts of C atom number from 1 to 10, and metalalkoxides of C atom number from 1 to 10) are used as precursors, whichare dissolved in a mixture of water and ethanol (the weight content ofwater in the mixture is 10-100%); after the hydrolysis and condensationof the precursors, stable transparent sol system is formed from theabove-mentioned solution; aAfter aging the sol, a three-dimensionalnetwork structure of the gel is formed slowly by the polymerizationbetween sol particles; after drying in air, inert gas or vacuum andbeing solidified, the target catalysts are obtained; Porous Si-basedmaterials impregnation method: using a porous solid silicon-basedmaterial (such as one or more of silica, silicon carbide, and siliconnitride) as a catalyst support, the support is impregnated in thesolution of metal salt for metal loading; after the impregnation, theslurry is dried; the resulting powder is melted in air, inert gas orvacuum and then solidified, the target catalysts are obtained; thepreparation methods of the said catalysts include an important meltingprocess, which includes an important melting step such ashigh-temperature air melting process, high-temperature inert gas meltingprocess, or high-temperature vacuum melting process. The preferabletemperature of the melting process is 1300-2200° C.; the inert gas inthe high-temperature inert gas melting process includes one or more ofN₂, He, Ar, and Ke; the vacuum in high-temperature vacuum meltingprocess is preferably 0.01-100 Pa.
 19. The catalyst according to claim18, wherein: the said solidification is that the catalyst preparationinvolves an important cooling process after the melting process; and thesaid cooling process includes rapid cooling or natural cooling; the saidrapid cooling process includes one or more of gas cooling, watercooling, oil cooling and liquid nitrogen cooling; the rate of the rapidcooling process is preferably 50-800° C./s; the type of oil in the saidoil cooling process includes one or more of mineral oil (saturatedhydrocarbon content of 50-95%, S content of ≦0.03%, a viscosity index(VI) of 80 to 170), rapeseed oil, silicone oil, and PAO (poly-α olefin);the type of gas in the said gas cooling process includes one or more ofinert gas (He, Ne, Ar, Ke), N₂ or air.
 20. The catalyst according toclaim 18, wherein the melting time is preferably 2-10 hrs.
 21. Thecatalyst according to claim 18, wherein: after being melted andsolidified, the amorphous-molten-state catalysts involve an importantstep of grinding or molding process; the particle size after beingground is preferably 10 nm-10 cm; the said molding process is that theamorphous-molten-state catalysts being melted are manufactured to obtainthe specific shape to meet various reaction processes, or directlymanufactured into tubular reactor.